Low concentrations of chemical species (analytes) targeted for detection and analysis pose unique technical challenges. Because low-concentration detection and analysis of some chemical compounds necessitate large and heavy lab apparatus, field deployment is often rendered difficult or impossible. In addition, the targeted analytes may be contaminated and/or mixed with false-positive compounds that confound accurate detection and analysis.
By definition, low concentrations generally represent a high ratio of inert or untargeted compounds to the targeted compound(s), often necessitating a process of filtering or other concentration processes, and with or without isolation or removal of contaminants. Thus, preparation is required to isolate and concentrate the analytes prior to the detection/analytic process, also inhibiting field portability.
There is a need for apparatus and processes that are both field portable and accurate, yielding minimal false-positive and false-negative detection events, and offering accurate and repeatable detection/analysis of the targeted analyte(s). Applications include chemical detectors (e.g., hand-held chemical detectors or automated chemical detectors) for low-concentration analytes such as drugs, explosives, chemical and/or biological agents and weapons used in terrorist activities, and biological metabolites.